< Mentor Note -- Thread moved from the Calculus forum to HH/Calculus > Hey everyone, I've started my new course and have been given revision and tutorial questions to do at home, this question has been bugging me for days now! I need to make "t" the subject to allow me to progress into the solution further. Make t the subject in " i=12.5(1-e^-t/cr) " I know that i need to use natural logs (ln) however i cannot seem to transpose the equation correctly. Could you please help me transpose this. Thanks Ramjam p.s forgot to add my working so far, DUH! ive transposed it to this form so far i/12.5 = 1 - e ^-t/cr this is where the logs come in and i have trouble, im not sure what to do next?!?